At the beginning of a game session I have my players give me 10 d20 rolls which I record. Then, when necessary for suspense, I take the next d20 roll I have written down for a player and add in their bonuses for the skill in question. Then I cross it off the list. When I have to ask a player for a new set of 10 rolls because I've used all theirs up, they always assume they missed a ton of spot checks heh.
So I guess I never actually roll a skill check for players. Although sometimes I do have them make rolls, sometimes real, sometimes bogus, just to add to the suspense.